This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
Over the past 20 years, there have a number of instances where nuclear power plant operators have discovered gas voids—typically, air but occasionally other gases such as undissolved hydrogen—in fluid systems that are important to reactor safety. Typical fluid systems can be emergency core cooling systems, decay heat removal systems, and containment spray systems, to name a few. The amount of gas voids has, in some cases, been sufficient to call into question the operability of the fluid systems, if and when they are needed. In fact, initiation of a fluid system with gas voids present may lead to gas binding of its pumps, or destructive water hammer, for example. The sources of the gas have been various and are not readily controlled, thus detection of these voids is pertinent to various industries.
The need for nuclear plant licensees to manage gas accumulation has been formally identified in Nuclear Regulatory Commission generic letter 2008-01. The letter points out a need for continuous monitoring to detect and quantify gas voids in these systems, to ensure their availability in accordance with design basis requirements. The letter further notes that periodic functional tests of the critical systems will not provide the required assurance of operability; if a test finds a system's functionality questionable because of gas accumulation, the question of how long its operability has been compromised is unanswered.
The system disclosed herein addresses these issues definitively. It provides the ability to detect the onset of void formation in any one of multiple pipes in multiple systems on a continuous basis and, following void formation, the ability to quantify the amount of these voids, again continuously.